Why major web search engines are different

Major web search engines usually look for documents containing at
least one of the words you entered. They try to sort the best matches
(by some trade secret scheme) to the top of the list.

The H-Net engine only returns matches in which all your words appear.
It still tries to sort them in some manner; you get to choose whether
you want them in "best match" order, or by thread or date. Best match
isn't well defined here either, but it has to do with the idea that
clusters of hits in the same sentence or paragraph are more likely
to be good than random scattered hits. More hits is also better, though
sheer numbers won't necessarily bring a message to the very top.

The former is a better approach if you're trying to find ANY answer
to a question. The latter is better if you're trying to fine tune
things to get THE answer, or perhaps ALL answers, to a question.

The former tends to produce thousands of matches, most of which are
irrelevant. The latter tends to produce smaller result sets.